What came first?

"I suspect the distress comes first and the risky driving is just another manifestation of that distress," she says. "Because you can develop depression and anxiety quite early in your teens and that's long before you can actually be on the road."

Scott-Parker says she is now carrying out a longitudinal project to determine which comes first.

Previous research in New South Wales studied the relationship between psychological stress of young drivers and their crash history in the following two years and found no clear link.

"However two years is a very long gap," says Scott-Parker. "Your depression and anxiety levels could change significantly in that time."

Her research is across a six-month period and is also looking at driving behaviour itself rather than crashes as a key indicator of risk taking.

Scott-Parker says the findings could lead to better screening of adolescents at risk from both psychological stress and dangerous driving.

It suggests that people being treated for anxiety and depression should be counselled on safer driving, she says.

Similarly, she adds, it suggests people who are engaging in risky driving may have undiagnosed anxiety or depression that needs evaluating and treatment.